Data centers are parts of buildings or facilities in which a large number of computing and networking IT equipment, such as server computers, are mounted in racks that are arranged in the data center. The dense packing of the server computers results in the generation of a large amount of heat in a localized area. Too much heat may cause premature equipment failure. In addition, too much humidity can cause premature equipment corrosion, while too low can cause static electricity that damages the equipment. As a result, the data center must be cooled in a reliable manner in order to avoid the shutting down of, or damage to, the server computer hardware. Shutting down of server computers due to heat overload can cause significant economic loss.
To cool and control humidity of the racks of the data center, air conditioning systems, often specialized cooling units, have been developed for implementation directly in data centers. The specialized cooling units are sometimes known in the art as computer room air conditioning units (“CRACs”) or computer room air handling units. One of the main challenges of cooling data centers is the air conditioning system is often operated at or near maximum cooling and/or power while some racks and/or servers are still running too hot.
Besides the challenges of cooling data centers, there can also be large power consumption associated with powering the data centers in addition to cooling data centers. Thus, power consumption and inefficiency with data centers are key concerns. This is especially true in the scenario of expending more power for cooling than for running IT equipment, and in the scenario of maximum cooling and power requirements limiting the amount of additional IT equipment that can be later added to the data center. As a result, the use of metrics for characterizing data center efficiency has been developed in the industry. For example, one such metric is power usage effectiveness (PUE) which is calculated by measuring the ratio of total facility power consumption (power equipment, cooling equipment, and other) to “useful” power consumption, i.e., IT equipment. A PUE of 2.0 indicates that for every watt of power used for IT equipment, one additional watt is consumed to cool and distribute power to the IT equipment. Another metric is compute power efficiency (CPE) which takes into account computational efficiency as well as total facility power consumption and IT power consumption. CPE is calculated by measuring the ratio of IT equipment computational efficiency to PUE.
While certain air conditioning system arrangements provide a solution to the need for enhanced cooling power within a data center, there is nevertheless a danger of individual server computers overheating, due to at least imbalanced loading of processing tasks within the data center, malfunction, mislocation or inefficiency of the air conditioning system. It is therefore desirable to reduce the risk of overheating or other malfunction of one or more server computers in a data center, while optimizing PUE and/or CPE of the data center.